Jesus told the disciples that they would face pressure from the world, likely for them to be ready when that happens. In the process, Jesus talks about the condition of the pressurers.
First, Jesus talked about how if Jesus did not come and speak to them, they "would have no sin", but since Jesus spoke, "they have no excuse" (15:22). By the way, it's worth noting that the Greek word for "have" (Strong 2192) can mean "consider", and the meaning makes sense because the pressurers would not go against Jesus or have to consider their effects of their sin if they never encountered Jesus in the first place. However, since they did know their condition and learned about Jesus's credentials, they are guilty. As Jesus's works demonstrate his authority, Jesus makes a similar statement with his works (as written in 15:24). However, from rejecting Jesus, as Jesus has strong connections with the Father and has been endorsed by the Father, Jesus proclaimed that those who hate Jesus also hate the Father (15:23). The rejecters hated Jesus, so they in turn also hated the Father.
Additionally, Jesus told that the rejection happened to "fulfill" a prior Scripture that talked about how a group of people hated "without a cause" (15:25). The Scripture in particular is from Psalm 69, where David also faced pressure and stress from a lot of people who hated him for no good reason. The descriptor of hate for no good reason also fits those who strongly reject Jesus to the point of wanting to capture Jesus (hence "fulfilling" Scripture). For more information on "fulfilling", Christopher Smith had an article on Good Question Blog.